Brashening of wool



J. BAUER BRASHENING OF WOOL Filed Oct. 2l, 1948 ZOO |60 |80 'L00 220 240 260 ZBO 500 REVOLUTONS OF SAMPLE. IN THOUSANDS,

IDO

j INVENTOR m5,., ACL@ ATTORNEYS Patented Oct. 9, 1951 "UNITED STATE S PATENT OFFICE BRASHENING OF WOOL Jackson Bauer, Newportville, Pa., assignor to Fred Whitaker Company, a corporation of Pennsylvania Application October 21, 1948, Serial No. 55,765

8 Claims.

The present invention relates to the treatment .of wool and to wool pile fabrics produced by such treatment.

A purpose of the invention is to impart to wool .the characteristics associated with brashness, and thus to permit the conversion of non-brash 'South American wools into brash wools as required, and to enhance the brashness of wool having some brashness'. Y

A further purpose is to increase the wear resistance of woolen pile fabric such as upholstery, Acarpets and rugs.

A further purpose is to obtain greater wiriness, or stiffness combined withv re- .sili-ence, in wool.

A further purpose is to create or enhance arthe characteristics associated with dyeing, spinning, lubricating, weaving and subsequent laundering of the fabric.

A further purpose is to apply silica s-ol on the ,acid side under conditions which tend to agglomerate the sol and form gel, but without exhaustl.ing the solution by precipitation and to introduce such gross silica agglomerates to and in the wool. A further purpose is to avoid the presence of A further purpose is to carry on the treatment in a normal wool treating solution such as a bleach.

A further purpose is to aid the application optionally by including of a dispersing agent, a substantive agent or an impregnating resin.

Further purposes appear in the specification and in the claims.

`woolen pile fabric of the character to which the 'Kinvention is applied.

`loil especially ask oil emulsion during the treaty ment.

Figure 2 is a curve useful in explaining the,

invention.

'ways and the detail of production of the sols forms no part of the present invention. For example, nely divided silica can be put through a vc'olloid mill with water and converted to a silica sol. The particle size of the silica for this purpose usually is in the range between l0 and 50 'millirnicrons Likewise, the sols can be made chemically as for example according to the process of any of the following U. S. patents: White, No. 2,375,739; Bird, No. 2,244,325; Powers et al., No. 2,443,512; Marshall, No. 2,285,449; and White, No. 2,285,477.l The particle size of this chemically prepared material is usually of the order of V20 to 60 or 40 to 80 millimicrons, and for the present purpose the silica sol may vary from l0 to millimicrons initially, but the smaller silica particles in order to become effective will be greatly increased in size during the treatment as explained below. The silica of the sol will in many cases be hydrated by the method of preparation used.

- In the prior art treatment of textiles with silica sols, the effort has been to improve spinability and to increase tensile strength. The treatment has been very fugitive, and one of the advantages urged for the prior art wool treatment has been that it is completely removed from the iiber or cloth by a mild wash. q

Y The present invention is concerned with a wholly different purpose from the improvement of spinability or tensile strength. It has been recognized for many years that satisfactory production of woolen pile fabrics such as carpets and upholstery requires the use of a wool having certain characteristics. Y

The wool must remain upright in the pile yarn and the pile fabric made from such yarn should possess the property of restoring itself to itsoriginal upright position after it has been depressed.

4and a wool having such characteristics is herein referred to as brash or brashy For. the purposevof this application the characteristics which produce brashness are defined as a combination of those characteristics exhibited in carpet wool which are described as coarseness, roughness, harshness, stiiness, hairiness, and wiriness, combined with the requisite resilience and resistance to deformation or stress.

The exact cause of the condition of brashness is apparently not fully known, since two wools may have the same fiber cross sections and other observable physical characteristics, and yet one wool will be generally suited for carpet wool purposesv while the other will not. Thus there are large quatities of South American wools which are of suitable fiber cross section for use inthe best pile fabrics, but which are precluded from general use for such purpose because oi lack of brashness. There are also wools which have only slight brashness and can only be used to small extents in brash blends. l

The same characteristics which are above discussed in reference to pile fabrics are useful also in other fabrics, wherever a brashy wool is required.

I have discovered that the characteristics `associated with brashness can be imparted artiunlike the previous treatments intended toaid spinability, brashness can be permanently im'- parted so that the wool will remain brash` throughout the process and after subsequentV laundering of the fabric. I have also discovered that by the same treatment the wear resistance of the p-ile can be tremendously increased.

Thus in accordance with the invention a South- American or other non-brash wool can be converted permanently into a woolT which1exhibitsy the desirable characteristics of the better grades of carpet Wool. been considered soft for their particular liber size-andfaccordinglyhave been known as blanket or clothing wools, canbe converted completely into Woolsl suitable for carpet' and upholstery use.

The effect? of" the treatment will be substantially resistant to several hours ofv boiling in Water, and tov the'normaldyeing, spinning, lubricating, Weaving and laundering operations, so that itv can be applied at an early stage-in the processing of the wool. Itfis not, however, prac.- tical to-apply it in the picker With the` oil'emul'- sion, as thedesired brashness-isnot acquiredand the slight results obtained are not permanent-l;`

It is of incidental but considerable benetthat the treatmentV likewise serves'to-deluster the wool, thus avoidingfthe necessity of separate d'elusteringv where required.

I- have discovered that it is not possible toobtain permanence in the treatment unless the wool is previously degrea-sed to a total grease content of less than 1.5% and preferably less than before treatment. The percentage is-based on the dry weight of the wool. If` the wool is treated inthe grease,- I find' that' the treatment is'- not permanent and is otherwise unsuitable: The grease content should normally run between' 1 and after scouring and before treatment with silica, and I prefer to scour to atotal grease content ofAV 1/2% orless. In any case, otherfactorsinvolved being equal, as the grease content increases, theeiiectivenessor the'treatment decreases. Whenever grease contenti is reterredfto herein, it isintendedtodeSignategrease content asmeasured upon extraction by carbon tetra*- chloridev at room temperature. Where-degreasincris referred to'it is intended'to include solvent scouringas Well as soap ordetergent scouring.

Iy havealso discovered that the'V remarkable resultsY obtained by theV present inventionv are not producedv unless thel operations are` performed under acid conditions. Theacidity may beimpartedA in either of two ways, either as'acidity in the treating solution or acidity previously imparted to the wool.

Without limiting myself to the theory herein set forth, my experiments indicate thattheeffect of acidity is to cause the particles of silica sol tov agglomerate and produce gross particles which enter intothewool fiber formingV a silica matrix, and. also to. someextent deposit ontheber. I believe. that the-scouring or degreasing to the extent indicated is necessary to permit penetration throughthe'epidermis of the-ber, so that aynetworkV or matrix of Silica can build up in the cortical layer or'themedulla, either in the porous air channels which are there presentV or' in or among, the cells or iibrils. A further reason for removing grease is thatY the presence of a grease film in or onY the fiber may prevent such bonding between the wool and the silica as mayV bei the result, ofK the existence of opposite electrical chargesforrV the Wool and the silica. My experimentsindicate.that the improved properties are Thus Wools which previously had' notfdueto. increase in externall diameter, but are dueto action' primarilyfwithin the fiber or on the surface but in such amounts as not to affect fiber diameter.

The extreme firmness of adhesion obtained suggests that the disposition of the silica is not purely physical'but' involves the operation of secondary valences, and is therefore also chemical.

Ensamble I A, control was used for comparison with the treated sample which consisted of a high grade India carpet wool. The sample to be treated was a South America-n wool havingI the same approximate-fiberfsize as the control, butY initially having a comparatively softfeeland`-knownin the trade as. a blanketA wool`A or clothing' wool. The'wool to be treated was scoured'in'theordinary manner to a total grease content of"'0:'3f%'. The degreased" wool was then treated continu-- ousely yin a Vfull size standard' wool, bowl, withJ a solution consisting of Water containingi0'6 %1 of silica sol madeby diluting commercialf'sili'ca' sol dispersionwith Water' tothe concentration men"- tioned. The solution also `contained 40:1 75L off-sulphuric'acid; The solutionwas free from oilf The Wool was passed throughthe' bowl:l under ordinary' conditions, at a rateV` Whichf assured" exposure to the solution for about 1'1/2 minutes. The temperature of the solution was' 1I'5V"'F.

Under these conditions;,in` the presenceof; the normal impurities brought into the sol'utionby the wool, the particles Lof'silica agglomerate'd, and a, small amount of 4precipitate:formed as the im'- purities carried in with the wool actedon the solution. rlhis is not objectionable; The' Wool picked upy silica in proportion tok thepick-upof solution, which was controlled'bysqueezerollsat the end of the'bowl. Y,

After passing'through theitreatingf'bath, and squeezing to remove excesstreating' liquid; the wool, when inspected in the wetshovved. little evidence of change in brashness. The woolwas then carried through a standard' wooldrier"l and brought to equilibrium with the atmosphere of the room. After the moisture content; had reached equilibrium with the atmosphere' a't about 12%, the treated Wooly/as' compared with the control- A remarkable change inibrashness ofr the treatedV Wool was noted.v The South American: wool, whichY formerly Wasi soft` and appeared, obviously unsuitable for'pile fabrics, now was, found to be brashier than the control.

The wool'was then further processed, spuninto yarn, dyed, and made intopile fabric.

The treated wool'in the pilev ofthe pile fabric was found upon test to have the stiiness'and'resilience characteristics required.. for carpet` Wlool or other pile fabricivoohquite unlike the. characteristics or" the untreated wool, and quitaunlike the characteristics of wooLtreatedwith silica sols byprior art methods.

A sample of the'treatedV woolwas brought. toa boil in Water over a=periodzofr35rminutes and then boiled for 40 minutes. The sample was subsequently'dried and exposedY to Athe airof the .room for a suihcient time to bring it to equilibrium as toV temperature and moisturecontentv with the warehouse. Itwas foundby comparison-with-a treatedsample which hadfnot-undergone boiling, that the: brashness imparted by ther treatment was substantially retained duringv the.` boiling. Similar experiments were 'made to determine the effect on the brashness of normal Wool treatments such as: fur-ther processing dusting,lv spinning.

weaving and laundering, and it wasfoundthat the brashness is retained with very slight loss during such further treatments. 1

Example II The treatment above referred to iii-Example I was applied to a dyed carpet Wool blendcontaining small quantities of wool of inferior brashness, retaining a sample of the same blend untreated as a control. The treated sample and the control were then spun into carpet yarn and woven into velvet carpet, after which both samples were tested by U. S. Testing Company on the National Bureau of Standards carpetwear4 tester. The pile in each case was worn down to 1A; lof the net crushed pile height under the standard procedure, op-erating at 72 F. and 65% relative humidity. Figure 2 illustrates the bestA results, plotting net pile height in thousandths of an inch as ordinate and revolutions of tester, undergone by sample as abscissae. Curve I is for the treated sample and curve 2 is for the control. This shows that the sample of the untreated carpet wool blend withstood 120,000 revolutions to failure while the sample of the same Wool blend treated according to the invention withstood 300,000

" revolutions to failure or an improvement of 130% in wear resistance. In every other respect which could be determined by observation and tests applied, the treated sample was equal to or superior to the untreated sample. The treated sample exhibited enhanced brashness and the improvement in brashness of the treated sample is believed to lbe responsible for the improved wear resistance. A 50 hour fadeometer test showed no unfavorable effect on the dyeing when the carpet made from the treated wool was compared with the control.

Example III strengths. The solution performed the functions lof the bleach normally used besides applying the treatment in accordance with the invention. The

product was from the standpoint of the invention identical with that of Example Il.

Eample V A series of experiments werecarried out using various concentrations of acids. It was found vthat as the acid concentration increased, the

tendency to agglomerate the silica particles increased, and when the pH reached the acid side of 2, the dusting of particles deposited on the surface became prohibitive in further processing. Thus beyond this pH value the desirable eiect on the brashness of the fiber is clouded by the undesirable tendency to form surface deposit. It was found by this series of experiments that the desirable brashness can be obtained using a pH range inthe bath between 2 and 6, but pH ranges on the acid side of 2 are not practical because of eventual excessive agglomeration in the continuous processing, and pH ranges on the alkaline side of 6 do not give satisfactory-improvev ment in brashness or permanence in deposit unless the technique of acidifying the wool itself is used as referred to below. Best vresults from the standpoint of improvements in the characteristics associated with brashness and elimination of dusting areobtained using pH ranges between 3 and 5. Y

Example VI Using the procedure of Example I and the pH ranges of Example V, alkaline scoured wool was treated after having been first acidied to various pHs on the wool. It was found that the treatment would proceed satisfactorily even though the resultant wool was alkaline to a pH as high as 8, but that desirable results were not obtained when the pH on the wool was on the alkaline side of 8. In determining the pH on the wool, the procedure used was to dilute five grams of dry wool with milliliters of distilled water, which had been boiled to expel carbon dioxide. The wool is placed in the boiling water and agitated during cooling of the water to room temperature, after which the pH of the solution is taken as the pI-I on the wool.

Example VII The procedure of Example I Iwas repeated, adding a dispersing agent to maintain the dispersion of the silica in the presence of impurities brought in by the wool. The dispersing agent used was an alkyl naphthalene sodium sulphonate, methyl naphthalene sodium sulphona-te in a concentration of 0.1%. It was found that the dispersing agent made it possible to operate for a longer period without dropping the bath, and reduced the tendency to form precipitate.

The alkyl naphthalene sodium sulphonates generally are suitable. Other dispersing agents were used successfully, including sodium hexametaphosphate, tetrasodium pyrophosphate, sodium tetraphosphate, naphthalene sulphonic acid condensed with formaldehyde, and naphthalene sulphonic acid derivatives condensed with formaldehyde. It was `found that any water soluble dispersing agent might be used and that the aromatic sulphonates and aromatic sulphonic acids were most suitable. The concentration of dispersing agent may vary from 0.01 to 1%.

Example VIII The procedure of Example I was repeated with the addition of a dispersing agent as in Example VII followed by the additionA of 0.1% of a substantive agent. Suitable substantive agents are quaternary ammonium salts, such as aliphaticaromatic quaternary ammonium halides, examples of which are trialkyl benzyl ammonium chloride, as for example trimethyl benzyl ammonium chloride, triethyl benzyl ammonium chloride, dimethyl ethyl benzyl ammonium chloride, diethyl methyl benzyl ammonium chloride, benzyl cetyl dimethyl ammonium chloride and benzyl cetyl diethyl ammonium chloride; also tetra alkyl quaternary ammonium halides such as trimethyl cetyl quaternary ammonium chloride, triethyl cetyl quaternary ammonium chloride. The concentration of substantive agent may vary from 0.01 to 1%. In the case of substantive agents, there is a tendency to exhaust the bath, and such exhaustion must be made up by controlledvadditions of silica sol tothe bath, and limiting the time of treatment in accordance with the desired pick-up. There is a further tendency to induce undesirable precipitation which should be inhibited by the use of increased quantities of dispersing agent.

Additional experiments indicated that any other suitable acid can be used instead ofsulnacids when the pH was the same. is capable of operation with hydrochloric acid, oxalic acid, citric acid, phosphoric acid or any `as desired.

open tank, dyeing machine or the like, the time v will vary to suit the particular equipment.

. ofadye bath.

Y 0.1 to 5% of lthe bath.

phuric acid, -resu1ts identical with vthose set -vforth .nfExample I having been lobtained with other The invention other suitable acid.

The concentration of silica sol in the bath may vary from 0.3% to 5%, and the pick-up of silica :may vary from 0.1% to 2% on the Weight of the dry Wool.

In the absence of a substantive agent, the timek Uof exposure is not critical as long as the wool is thoroughly `wet lby the treating bath. For good results in continuous treatment it is notwise to use an exposure time of less than one-half rnin-` I.

ute and the usual exposure time is about one and one-half minutes, but in the absence of substantivity the time may be extended indefinitely Where batch treatment is used in an The temperature used may vary from the ambient up to close to a boil, although a temperature in excess` of about 125 F. is not desirable as it is unduly destructive of the sol. The treating solu tion has a wide degree of compatability. As' pointed vout a bleaching agent such as hydrogen peroxide (suitable in a concentration of 1 to 3 `v olume strengths) may operate inthe same bath. Y. Likewise the treatment of the invention may .be

appliedbefore orafter dyeing or in the presence Example IX ldispersions of other synthetic resins may be used in the treating bath, typical examples being acrylic, phenol-formaldehyde and melamine, in Asuch form as to be stable in the desired pH range. Oil emulsions should however be avoided.

Example X Instead of using a treating solution within the acid range specified, acidity may be imparted to the wool. The procedure of Example I was followed, with the additional step of acidiying the f Awoolby treatment with 0.1% sulphuric acid subsequent to the degreasing and prior to the exposure to the silica sol. The silica sol was maintained at pH 7, omitting the sulphuric acid in the silica sol solution. The exposure time was limited so that the pH of the wool at the time it was extracted and removed from the treating bathY was on the acid side of 7 TheY results obtained were comparable to those secured in Example I, but the treatment was more critical in that the exposure time required careful regulation. Where reliance is placed on acidulating the wool, the pI-I of the wool at the time it enters the solution of silica sol should be between 2 and 6. The pH of the solution may in this case vary between 6 and 8, and the pH on the wool at the time it leaves the treating solution should be on the Yacid side of 7. It will be observed, of course, that if the pI-I of the silica sol solution is between 2 and 6 rather than between 6 and 8, the operation is effectively the same as that of Example I.

dyed carpet wool blend using spraying of the Example 1I. The'results were less uniform ,than those obtained in Example II but were otherwise generally similar. There was a much more pronounced surface deposit and more dusing presentfin the case of application by spraying than was characteristic of the immersion treatment. The permanence of the treatment was also in- Yferior to that, obtained byimmersion and for this reason thespray treatment is not regarded as preferable.

VIn ordinary practiceithe wool, after drying and reaching equilibrium at room temperature will yhave'a moisture content of the order of 12%.

It Ishould be emphasized that the improvement in the characteristics associated with brashness produced by the invention will usually not be obvious While the wool is moist, but will in most cases only be recognizable when the wool has reached an equilibrium moisture content comkcombined, with resilience in, aY pile ofa pile fabiric. Yliigu'rejl.illustrates a pile fabric having a backing-,276; and pile yarn 2l which has been treated inaccord-ancewith the invention. The

pileyarn-ZI will,.;in the vnormal case, have no measurable increase in diameter dueto the treatment, but' will Adefinitely Vbe Vimproved in characteristics associated .with brashness, particularly ,in the combination1 of resilience and stiffness sometimes called wiriness, and in remarkable increase in wear resistence. Thus the pile remains upstanding Nlonger and rwill wear away more slowly than similar wool pile not having this treatment. Likewise the pile is desirably delustered "by the treatment. The cost of the pile is considerably decreased, since the cost of soit wools such as South American blanket and clothing wools is generallyV less than that of high grade carpet wools.

The pile 2| has the remarkable property of retaining its/improved characteristics notwithstanding vusual treatments such las laundering, and even after several hours of boiling. Dyeing can beappled to the fabric without loss of the Vimproved properties.

In essence my ,experiments indicate that a matrix or network of silica is introduced to the fibers of the pile-2l which appears to combine chemically, apparently due to secondary valence.

Vproduce gross aggregates Ywhich enter the liber and stiffen and increase its wear resistence.

In the process of `formation and entry into theber it would appear that Ythe Ysol'converts to gel, at least in part, and that the gel contributes to obtaining 'the unusual properties. This conclusion is confirmed vbythe vfact that under normal operating conditions a small amount of silica precipitates from the'treating bath, apparently due to greatly excessive agglomeration.

The extent of agglomeration can'be controlled by varying thesilica concentration of the solution and Vmore especially by varying the acidity. The greater the acidity, the more pronounced the tendency to agglomerate and the greater the concentrationof silica the-greater the tendency to Iagglomerate. The wasteful precipitate can be retarded by the presence of a suitable dispersing agent, as mentioned, and where a considerable amount of foreign matter from the wool is being carried into the treating bath, the presence of a dispersing agent is very desirable to suppress the tendency of the impurities to throw down the sol and shorten the life of the bath.

Oil emulsion should be avoided 'and it is very undesirable to attempt to apply the present invention in a bath where cil emulsion is being used, as in the picker where silica sol has previously been employed.

Providing the above precautions are followed, results can be obtained reliably without undue waste of chemicals.

When reference is made to imparting the characteristics associated with brashness, it will be understood that such characteristics may be either created or enhanced.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the process and product shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. The process of treating wool to impart characteristics associated with brashness, which comprises degreasing the wool to a total grease content of less than based on the dry weight of the ber, subsequently treating the wool at any stage in its processing with a solution consisting of an acidied aqueous dispersion of colloidal silica of yan initial silica particle size between 10 and 100 millimicrons and having a pH of 2 to 6 until the pick-up of silica by the wool is in the range between 0.1 and 2% based on the dry weight of the ber, and drying the wool.

2. The method of increasing the wear resistance of wool for pile fabrics, which comprises degreasing the wool to a total grease content of vless than based on the dry weight of the ber, subsequently treating the wool with a solution consisting of an acidiiied aqueous dispersion of colloidal silica of an initial silica particle size between 10 and 100 millimicrons having a pH of 2 to 6 until the pick-up of silica by the wool is in the range between 0.1 and 2% based on the dry Weight of the ber, thereby agglomerating the silica and forming gel in the solution, and then allowing the wool to dry.

3. The process of imparting to wool the characteristics associated with brashness, which comprises degreasing the wool to a total grease content of less than based on the dry weight of the fiber, treating the wool in a solution consisting of an acidied aqueous dispersion of colloidal silica of an initial silica particle size between 10 and 100 millimicrons and having a pH of 2 to 6 in the presence of gross agglomerates of silica formed under the influence of the acid until the pick-up is in the range from 0.1 to 2% silica based on the dry weight of the fiber, and then drying the wool.

4. The process of treating wool, which comprises degreasing the wool to a total grease content of less than based on the dry Weight of the ber, treating the wool in a solution consisting oi an acidied aqueous dispersion of colloidal silica having a pH of 2 to 6 of an initial silica particle size between 10 and v100 millimicrons and having a pH oi 2 to 6 in the presence of a dispersing agent and a substantive agent until the pick-up of silica by the wool is in the range between 0.1 and 2% based on the dry weight of the fiber, and drying the treated wool.

5. The process of treating wool to impart characteristics associated with brashness, which comprises degreasing the wool to a to-tal grease content below based on the dry weight of the fiber, treating the wool in a solution vconsisting of an acidified aqueous dispersion of colloidal silica of an initial silica particle size between 10 and millimicrons having a pH of 2 toy 6 and containing gross aggregates of colloidal silica until the pick-up of silica by the wool is in the range between 0.1 and 2% based on the dry weight of the liber, and drying the wool.

6. rlhe process of treating wool to impart characteristics associated with brashness, which comqrises degreasing the wool to a total grease content 4below based on the dry weight of the fiber, acidifying the wool to a pH on the wool of 2 to t, and treating the wool with a solution consisting of an aqueous dispersion of collodial silica of an initial silica particle size between 10 and 100 millimicrons, at a pH of 6 to 8 until the pH on the wool has increased to avalue toward the alkaline side of its original pH but still on the acid side of neutral until the pick-up of silica by the wool is in the range between 0.1 and 2% biased on the dry weight of the flbenand drying the wool.

7. A wood pile fabric in which the wool' fibers haveu a silica matrix imparted by degreasing the wool to a total grease content of less than based on the dry weight of the wool, treating the wool with a solution consisting of an acidied aqueous dispersion of colloidal silica of an initial silica particle size between l0 and 100 millimicrons and having a pH of 2 to 6 until the wool has picked up from 0.1 to 2% of silica based on the dry weight of the wool, and drying the wool.

8., A wood pile fabric in which the wool fibers of the pile have a silica matrix imparted by degreasing the wool to a total grease content of less than 121% based on the dry weight of the ber, acidifying the wool to a pH on the wool of 2 to 6 and treating the wool with an acidiiied aqueous dispersion of colloidal silica of an initial silica particle size between 10 and 100 millimicrons having a pH of 6 to 8, untilA the pH on the wool has changed toward the alkaline side but is still on the acid side of neutral and until the pick-up of silica by the wool is in the range between 0.1 and 2% based on the dry weight of the liber, and then drying the wool.

JACKSON BAUER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,629,241 Ubbelohoe May 17, 1927 1,961,863 Parker June 5, 1934 2,201,891 Edgar et al May 21, 1940 2,327,278 Lurie Aug. 17, 1943 2,443,512 Powers et al June 15. 1948 

1. THE PROCESS OF TREATING WOOL TO IMPART CHARACTERISTICS ASSOCIATED WITH BRASHNESS, WHICH COMPRISES DEGREASING THE WOOL TO A TOTAL GREASE CONTENT OF LESS THAN 3/4% BASED ON THE DRY WEIGHT OF THE FIBER, SUBSEQUENTLY TREATING THE WOOL AT ANY STAGE IN ITS PROCESSING WITH A SOLUTION CONSISTING OF AN ACIDIFIED AQUEOUS DISPERSION OF COLLOIDAL SILICA OF AN INITIAL SILICA PARTICLE SIZE BETWEEN 10 AND 100 MILLIMICRONS AND HAVING A PH OF 2 TO 6 UNTIL THE PICK-UP OF SILICA BY THE WOOL IS IN THE RANGE BETWEEN 0.1 AND 2% BASED ON THE DRY WEIGHT OF THE FIBER, AND DRYING THE WOOL. 